This invention relates generally to a tape cassette comprising a housing, at least one reel hub rotatably mounted within the housing and a magnetic recording tape wound around the reel hub, and more particularly, to a mechanism for preventing the magnetic recording tape wound around the reel hub from loosening.
In a conventional tape cassette, the reel hub is freely rotatable within the housing of the tape cassette and is slightly movable in its axial direction except at the time when the tape cassette is mounted to a magnetic recording tape running apparatus by engagement of the reel hub with a reel shaft of the tape running apparatus. In other words, the reel hub is substantially freely movable during, for example, transportation of the tape cassette detached from the tape running apparatus. Thus, the magnetic recording tape wound around the reel hub is loosened in the radial direction of the reel hub. In addition, deviation between two adjacent turns of the tape takes place in the axial direction of the reel hub. The loosening mentioned above brings about a marked difference in diameter between two adjacent turns of the tape, leading to a marked fluctuation in the magnitude of back tension exerted on the magnetic recording tape when the tape is run by a running apparatus. Naturally, the tape fails to be run at a constant speed. Where the tape cassette is mounted to, for example, a tape recorder, the nonuniform running speed of the tape causes wow and flutter, resulting in unsatisfactory quality of the sound recorded on and reproduced from the magnetic recording tape. The deviation in the axial direction of the reel hub mentioned above also causes the sound reproduced from the tape to be unsatisfactory where the tape cassette is mounted to a tape recorder, because deviation occurs between the track of the magnetic recording tape and the magnetic head in the width direction of the tape.